| Inner side slightly concaved; L/W=7-14 | 
| Cell body 20-40 μm in width | 
|   var. acerosum
 508 x 37.5 μm
 L/W=13.5
 Koaze river
 Saitama, 2002
 |   var. acerosum
 508 x 32 μm
 L/W=16
 Saitama, 2000
 |   var. acerosum
 363 x 36 μm
 L/W=10.1
 Saitama, 1999
 | 
|   var. acerosum
 314 x 34 μm
 L/W=9.2
 Motoyurugi
 Fujioka
 Gunma, 2004
 |   var. acerosum
 206 x 38 μm
 L/W=5.4 ?
 Saitama, 1999
 |   var. acerosum ?
 560 x 34 μm
 L/W=16.5
 Yamato
 Kanagawa, 2003
 |   var. acerosum ?
 530 x 35 μm
 L/W=15
 Ina town
 Saitama, 2003
 | 
|   var. acerosum
 450 x 34 μm
 475 x 34 μm
 L/W=13, 14
 Saitama, 1999
 |   var. acerosum
 470 x 37 μm
 L/W=12.7
 Akasaka-numa
 Iwatsuki-ku
 Saitama, 2006
 
  |   var. acerosum
 388 x 38 μm
 L/W=10.2
 Akasaka-numa
 Iwatsuki-ku
 Saitama, 2006
 
  |   var. acerosum
 338 x 33 μm
 L/W=11.8
 Saitama, 2001
 | 
|   var. acerosum
 334 x 27 μm
 L/W=12.4
 Nanbata castle p.
 Fujimi
 Saitama, 2004
 |   var. acerosum
 338 x 28 μm
 L/W=12.1
 Kaga
 Ishikawa, 2000
 |